Abstract: A method of placing concrete into a steel encasement constructing an offshore structure. The steel encasement is erected. A plurality of first concrete injection holes are formed through the steel encasement in a heightwise spaced manner. The concrete is injected through the lowest disposed concrete injection hole into the erected steel encasement to a level below another concrete injection hole disposed just above said lowest disposed concrete injection hole. Then, the injection step is repeated in connection with a subsequent first concrete injection hole nearest to the level, to which the concrete has been placed, for placing the concrete into the steel encasement to a predetermined level.

Abstract: Eddy current distance measuring apparatus includes a multiplier connected to one secondary coil of a pair of secondary coils in an eddy current sensor. The secondary coil outputs are inputted to a differential amplifier, and the resulting difference is adjusted to be zero when an object the distance to which is to be measured is not present. Thereafter, the sensor is located within measuring distance of, e.g., a steel plate, and the output of the differential amplifier is combined by an amplifier circuit with an oscillator output supplying a current to the primary coil of the sensor. An eddy current distance signal output is thus obtained.

Abstract: The mobile marine drilling structure is of the submersible type for operation in ice-covered waters. The structure comprises a base for placing the structure on the sea bed, a hull extends from the base, and a deck is supported by the hull. The deck is located above the water line for conducting drilling operations. The hull has an internal frame assembly including ballast tanks, and external wall sections at different inclinations to the horizontal to engage and break up the moving ice masses encroaching on the hull. These external wall sections include a plurality of matching polygonal, frusto-pyramidal, apex-up and apex-down walls extending above the base, and two transitional wall sections to provide two inflection points to the hull.